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feat: add solutions to lcof2 problem: No.056.Two Sum IV - Input is a BST
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13 files changed

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-124
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13 files changed

+391
-124
lines changed

‎lcof2/剑指 Offer II 056. 二叉搜索树中两个节点之和/README.md

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<!-- 这里可写通用的实现逻辑 -->
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用哈希表记录访问过的节点。
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<!-- tabs:start -->
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### **Python3**
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<!-- 这里可写当前语言的特殊实现逻辑 -->
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```python
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# Definition for a binary tree node.
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# class TreeNode:
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# def __init__(self, val=0, left=None, right=None):
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# self.val = val
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# self.left = left
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# self.right = right
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class Solution:
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def findTarget(self, root: TreeNode, k: int) -> bool:
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def find(root):
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if not root:
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return False
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if k - root.val in nodes:
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return True
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nodes.add(root.val)
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return find(root.left) or find(root.right)
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nodes = set()
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return find(root)
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```
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### **Java**
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<!-- 这里可写当前语言的特殊实现逻辑 -->
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```java
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/**
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* Definition for a binary tree node.
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* public class TreeNode {
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* int val;
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* TreeNode left;
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* TreeNode right;
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* TreeNode() {}
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* TreeNode(int val) { this.val = val; }
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* TreeNode(int val, TreeNode left, TreeNode right) {
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* this.val = val;
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* this.left = left;
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* this.right = right;
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* }
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* }
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*/
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class Solution {
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private Set<Integer> nodes;
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public boolean findTarget(TreeNode root, int k) {
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nodes = new HashSet<>();
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return find(root, k);
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}
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private boolean find(TreeNode root, int k) {
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if (root == null) {
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return false;
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}
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if (nodes.contains(k - root.val)) {
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return true;
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}
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nodes.add(root.val);
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return find(root.left, k) || find(root.right, k);
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}
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}
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```
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### **TypeScript**
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```ts
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/**
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* Definition for a binary tree node.
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* class TreeNode {
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* val: number
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* left: TreeNode | null
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* right: TreeNode | null
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* constructor(val?: number, left?: TreeNode | null, right?: TreeNode | null) {
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* this.val = (val===undefined ? 0 : val)
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* this.left = (left===undefined ? null : left)
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* this.right = (right===undefined ? null : right)
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* }
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* }
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*/
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function findTarget(root: TreeNode | null, k: number): boolean {
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let nodes: Set<number> = new Set();
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return find(root, k, nodes);
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};
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function find(root: TreeNode | null, k: number, nodes: Set<number>): boolean {
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if (!root) return false;
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if (nodes.has(k - root.val)) return true;
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nodes.add(root.val);
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return find(root.left, k, nodes) || find(root.right, k, nodes);
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}
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```
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### **C++**
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```cpp
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/**
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* Definition for a binary tree node.
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* struct TreeNode {
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* int val;
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* TreeNode *left;
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* TreeNode *right;
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* TreeNode() : val(0), left(nullptr), right(nullptr) {}
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* TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
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* TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
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* };
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*/
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class Solution {
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public:
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unordered_set<int> nodes;
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bool findTarget(TreeNode* root, int k) {
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return find(root, k);
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}
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bool find(TreeNode* root, int k) {
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if (!root) return false;
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if (nodes.count(k - root->val)) return true;
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nodes.insert(root->val);
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return find(root->left, k) || find(root->right, k);
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}
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};
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```
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### **Go**
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```go
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/**
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* Definition for a binary tree node.
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* type TreeNode struct {
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* Val int
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* Left *TreeNode
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* Right *TreeNode
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* }
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*/
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func findTarget(root *TreeNode, k int) bool {
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nodes := make(map[int]bool)
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var find func(root *TreeNode, k int) bool
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find = func(root *TreeNode, k int) bool {
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if root == nil {
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return false
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}
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if nodes[k-root.Val] {
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return true
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}
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nodes[root.Val] = true
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return find(root.Left, k) || find(root.Right, k)
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}
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return find(root, k)
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}
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```
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### **...**

‎lcof2/剑指 Offer II 056. 二叉搜索树中两个节点之和/Solution.cpp

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Original file line numberDiff line numberDiff line change
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/**
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* Definition for a binary tree node.
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* struct TreeNode {
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* int val;
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* TreeNode *left;
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* TreeNode *right;
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* TreeNode() : val(0), left(nullptr), right(nullptr) {}
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* TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
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* TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
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* };
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*/
12+
class Solution {
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public:
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unordered_set<int> nodes;
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bool findTarget(TreeNode* root, int k) {
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return find(root, k);
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}
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bool find(TreeNode* root, int k) {
21+
if (!root) return false;
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if (nodes.count(k - root->val)) return true;
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nodes.insert(root->val);
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return find(root->left, k) || find(root->right, k);
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}
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};

‎lcof2/剑指 Offer II 056. 二叉搜索树中两个节点之和/Solution.go

Lines changed: 24 additions & 0 deletions
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/**
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* Definition for a binary tree node.
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* type TreeNode struct {
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* Val int
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* Left *TreeNode
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* Right *TreeNode
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* }
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*/
9+
func findTarget(root *TreeNode, k int) bool {
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nodes := make(map[int]bool)
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var find func(root *TreeNode, k int) bool
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find = func(root *TreeNode, k int) bool {
14+
if root == nil {
15+
return false
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}
17+
if nodes[k-root.Val] {
18+
return true
19+
}
20+
nodes[root.Val] = true
21+
return find(root.Left, k) || find(root.Right, k)
22+
}
23+
return find(root, k)
24+
}

‎lcof2/剑指 Offer II 056. 二叉搜索树中两个节点之和/Solution.java

Lines changed: 34 additions & 0 deletions
Original file line numberDiff line numberDiff line change
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/**
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* Definition for a binary tree node.
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* public class TreeNode {
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* int val;
5+
* TreeNode left;
6+
* TreeNode right;
7+
* TreeNode() {}
8+
* TreeNode(int val) { this.val = val; }
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* TreeNode(int val, TreeNode left, TreeNode right) {
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* this.val = val;
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* this.left = left;
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* this.right = right;
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* }
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* }
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*/
16+
class Solution {
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private Set<Integer> nodes;
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public boolean findTarget(TreeNode root, int k) {
20+
nodes = new HashSet<>();
21+
return find(root, k);
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}
23+
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private boolean find(TreeNode root, int k) {
25+
if (root == null) {
26+
return false;
27+
}
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if (nodes.contains(k - root.val)) {
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return true;
30+
}
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nodes.add(root.val);
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return find(root.left, k) || find(root.right, k);
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}
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}

‎lcof2/剑指 Offer II 056. 二叉搜索树中两个节点之和/Solution.py

Lines changed: 18 additions & 0 deletions
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# Definition for a binary tree node.
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# class TreeNode:
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# def __init__(self, val=0, left=None, right=None):
4+
# self.val = val
5+
# self.left = left
6+
# self.right = right
7+
class Solution:
8+
def findTarget(self, root: TreeNode, k: int) -> bool:
9+
def find(root):
10+
if not root:
11+
return False
12+
if k - root.val in nodes:
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return True
14+
nodes.add(root.val)
15+
return find(root.left) or find(root.right)
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nodes = set()
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return find(root)

‎lcof2/剑指 Offer II 056. 二叉搜索树中两个节点之和/Solution.ts

Lines changed: 25 additions & 0 deletions
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/**
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* Definition for a binary tree node.
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* class TreeNode {
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* val: number
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* left: TreeNode | null
6+
* right: TreeNode | null
7+
* constructor(val?: number, left?: TreeNode | null, right?: TreeNode | null) {
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* this.val = (val===undefined ? 0 : val)
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* this.left = (left===undefined ? null : left)
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* this.right = (right===undefined ? null : right)
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* }
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* }
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*/
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function findTarget(root: TreeNode | null, k: number): boolean {
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let nodes: Set<number> = new Set();
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return find(root, k, nodes);
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};
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function find(root: TreeNode | null, k: number, nodes: Set<number>): boolean {
21+
if (!root) return false;
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if (nodes.has(k - root.val)) return true;
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nodes.add(root.val);
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return find(root.left, k, nodes) || find(root.right, k, nodes);
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}

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